Selected iron and cobalt complexes of 2,6-pyridinecarboxaldehydebis(imines) and 2,6-diacylpyridinebis(imines) are catalysts for the copolymerization of ethylene and/or propylene and xcex1-olefins. Novel polymers may be produced.
Copolymers of ethylene and/or propylene and xcex1-olefins, such as linear low density polyethylene (LLDPE) are important items of commerce, millions of tons being produced annually. These polymers are used in a myriad of ways, such as for fiber, films, molding resins, etc. In most cases, ethylene and xcex1-olefins are copolymerized using a catalyst, often a transition metal compound or complex. These catalysts may vary in cost per unit weight of polymer produced, the structure of the polymer produced, the possible need to remove the catalyst from the polymer, the toxicity of the catalyst, etc. Due to the commercial importance of copolymerizing ethylene, new polymerization catalysts are constantly being sought.
B. L. Small, et al., J. Am. Chem. Soc., vol. 120, p. 4049-4050 (1998), and G. J. P. Britovsek, et al., J. Chem. Soc., Chem. Commun., p. 849-850 (1998) report the polymerization of ethylene using catalysts containing Fe or Co complexes of 2,6-pyridinecarboxaldehydebis(imines) and 2,6-diacylpyridinebis(imines). Copolymerization of xcex1-olefins and ethylene are not reported.
This invention concerns a first polymerization process, comprising, contacting, at a temperature of about xe2x88x92100xc2x0 C. to about +200xc2x0 C., a compound of the formula: 
with one or both of ethylene and propylene, and an olefin of the formula H2Cxe2x95x90CHR21 and:
(a) a first compound W, which is a neutral Lewis acid capable of abstracting Xxe2x88x92 an alkyl group or a hydride group from M to form WXxe2x88x92, (WR20)xe2x88x92 or WHxe2x88x92 and which is also capable of transferring an alkyl group or a hydride to M, provided that WXxe2x88x92 is a weakly coordinating anion; or
(b) a combination of second compound which is capable of transferring an alkyl or hydride group to M and a third compound which is a neutral Lewis acid which is capable of abstracting Xxe2x88x92, a hydride or an alkyl group from M to form a weakly coordinating anion;
wherein:
M is Co or Fe;
each X is an anion;
n is 1, 2 or 3 so that the total number of negative charges on said anion or anions is equal to the oxidation state of a Fe or Co atom present in (II);
R1, R2 and R3 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or an inert functional group;
R4 and R5 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl;
R6 and R7 are aryl or substituted aryl;
R20 is alkyl; and
R21 is alkyl.
This invention also concerns a second polymerization process, comprising contacting, at a temperature of about xe2x88x92100xc2x0 C. to about +200xc2x0 C., a Co[II], Co[III], Fe[II] or Fe[III] complex of a tridentate ligand of the formula: 
with one or both of ethylene and propylene, and an olefin of the formula H2Cxe2x95x90CHR21 wherein:
R1, R2 and R3 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or an inert functional group;
R4 and R5 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl; and
R6 and R7 are aryl or substituted aryl;
R21 is alkyl;
and provided that a Co[II], Co[III], Fe[II] or Fe[III] atom also has bonded to it an empty coordination site or a ligand that may be displaced by said ethylene, and a ligand that may add to said ethylene.
This invention also concerns a third polymerization process, comprising, contacting, at a temperature of about xe2x88x92100xc2x0 C. to about +200xc2x0 C., one or both of ethylene and propylene, an olefin of the formula H2Cxe2x95x90CHR21, and a compound of the formula: 
wherein:
M is Co or Fe;
R1, R2 and R3 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or an inert functional group;
R4 and R5 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl; and
R6 and R7 are aryl or substituted aryl;
R21 is alkyl;
T1 is hydride or alkyl or any other anionic ligand into which ethylene or an xcex1-olefin can insert;
Y is a neutral ligand capable of being displaced by ethylene or a vacant coordination site;
Q is a relatively non-coordinating anion;
P is a divalent polyolefin group; and
T2 is an end group.